合并两个有序链表

思路：穿针引线

ListNode* MergeTwoList(linkList headA, linkList headB)
{
	ListNode* pa = headA;
	ListNode* pb = headB;
	ListNode* headC = (ListNode*)malloc(sizeof(ListNode));
	ListNode* pc = headC;
	pc->next = NULL;

	while (pa != NULL && pb != NULL)
	{
		if (pa->data <= pb->data)
		{
			pc->next = pa;
			pa = pa->next;
		}
		else
		{
			pc->next = pb;
			pb = pb->next;
		}
		pc = pc->next;
	}
	if (pa != NULL)pc->next = pa;
	if (pb != NULL)pc->next = pb;

	pc = headC;
	headC = pc->next;
	free(pc);
	return headC;
}